Quadrant (instrument)

A quadrant is an instrument used for measuring angles up to 90 degrees. Different versions of the quadrant have been used for a variety of purposes, including surveying, navigation, and astronomy.

Historically, quadrants were used to measure the altitude of celestial objects, such as the Sun or stars, above the horizon. This information could then be used to determine latitude or to tell time. Early quadrants were typically made of wood or brass.

Several types of quadrants exist, each with its own variations in construction and function. Some notable types include:

• Astronomical Quadrant: Designed for precise astronomical observations, often featuring fine graduations and telescopic sights. Used for measuring the angular height of stars and other celestial bodies.

• Davis Quadrant (Backstaff): A navigational instrument used primarily for measuring the altitude of the sun. It allowed navigators to take measurements without directly looking at the sun, avoiding eye damage.

• Gunter's Quadrant: A versatile calculating instrument capable of solving problems related to time, the position of the sun, and other astronomical and astrological calculations. It incorporated various scales and curves to simplify these calculations.

• Surveyor's Quadrant: Used in land surveying for measuring horizontal and vertical angles.

The invention of the sextant eventually superseded the quadrant for navigational purposes due to the sextant's greater accuracy and ease of use, particularly on unsteady platforms. However, quadrants remained useful for certain specialized applications and for educational purposes.